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Author Topic: Manufacture Date: Columbia Carbon Bulb  (Read 1677 times)

Offline NZ

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Manufacture Date: Columbia Carbon Bulb
« on: January 08, 2020, 01:43:59 am »
Greetings and Happy New Year

I recently uncovered some bulbs that I don't seem to be able to find much about and would like to know a bit more about their manufacture date if possible.
The manufacturer is The Columbia Incandescent Lamp Co.
ST. LOUIS, MO.
100v, I have both 8 and 16cp versions as some still had a paper label with their rating.
Glass base, I'm guessing circa 1905?



There's a paper insert in the stem that has patent information that I've tried to capture.



Regards.



Offline NZ

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Re: Manufacture Date: Columbia Carbon Bulb
« Reply #1 on: January 08, 2020, 01:53:36 am »
Sorry about the size of the photos, I thought I had reduced them down more.
I also noticed that the tube with the patent information appears to be filled at the base with something that resembles horse hair?

Offline PCris

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Re: Manufacture Date: Columbia Carbon Bulb
« Reply #2 on: January 28, 2020, 03:48:46 pm »
Hello NZ,

I think your estimate c. 1905 is right in the ballpark.

The black glass insulator on the base began replacing earlier forms of insultation such as porcelain or plaster around 1901. The 8cp and 16cp (candle power) ratings were phased out on carbon filament lamps in 1910 (replaced by wattage ratings). So c. 1905 is a realistic estimate.

The filling in the stem is cotton wool, possibly used to prevent the lead-in wires from accidentally coming into contact with each other during manufacture of the bulb.

Best Regards,
PCris

Offline NZ

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Re: Manufacture Date: Columbia Carbon Bulb
« Reply #3 on: February 07, 2020, 07:54:28 pm »
Thanks for your reply and the info PChris, Cotton wool makes sense :)